This application is a request for support for the fifth Federation of American Societies for Experimental Biology Summer Research Conference on Neuroimmunology to be held at Wilsonville, Oregon, in July 1998. Scientists from a variety of disciplines have become increasingly interested in the dialogue between the immune system and the nervous system. In the past, the major effort in this field came from immunologists, who attempted to explain how the immune system affects nervous system behavior under pathological conditions such as autoimmune diseases of the nervous system. Little is known about the reciprocal effect of the nervous system on the immune system and even less is known about the bi-directional communication. This subject has recently attracted the attention of neurobiologists in general, and those working on CNS trauma and degenerative diseases in particular. As a result, it has now become clear that: (a) some components once thought to be exclusive to the immune system are also expressed by the nervous system; (b) there is a cross-talk between the immune system and nervous system, both in the intact and the injured CNS; and (c) the nature of the dialogue is unique in certain aspects to CNS while other aspects might be common to all tissues. In addition, the rapid advances in the field make it necessary to reassess a number of basic aspects of CNS-immune interactions, including anatomical, physiological and functional aspects of the CNS in relation to immune activity and interaction. In the past, interest in immune involvement in brain diseases was restricted to autoimmune diseases. Recently it became evident that almost any nerve-related disease involves an immune-associated component as part of its pathogenesis. This alters our view of therapeutic approaches currently accepted in the pharmaceutical industry for treatment of degenerative diseases of the CNS as well as treatment of CNS trauma. The basic aspects which should be reassessed include the role of microglia in degenerative and autoimmune diseases, CNS immune privilege, microglia in differentiation, their accessibility to the CNS and their role in trauma and degenerative diseases. It is important to assemble neuroimmunologists in their own forum, particularly since these processes involve input from several disciplines.